Here, we propose to demonstrate the feasibility of ameliorating symptoms of cystic fibrosis (CE) by administration of pro-drugs to affected tissues that deliver analogs of specific intracellular messengers, namely inositol polyphosphates, which regulate ion channels. We will test the hypothesis that a membrane-permeant inositol polyphosphate analog, lNO-E2, modulates sodium channel activity. Proof of this concept in epithelia from human CF airways would indicate the suitability of this approach for development as a CF therapeutic. Thus the specific aims are: Specific Aim 1: Determine whether JNO-E2 effects on current flux is due to its effect on ENaC. To test this we will measure the dynamics of the effect of INO-E2 and determine if it mimics the effect of the sodium channel blocker, amiloride. Specific Aim 2: Determine whether INO-E2 alters the driving force for sodium flux across the membrane. This could occur through primary interaction with other ion channels such as Calcium-activated Cl- channels and K+ channels. Specific Aim 3: Determine whether lNO-E2 could alter basal lsc indirectly through down regulating the membrane expression of ENaC. This will be tested in studies in collaboration with Sherif Gabriel at UNC, who will measure ENaC activity and expression in Xenopus oocytes.